Determination of Efavirenz in Plasma by Dispersive Liquid-Liquid Microextraction Coupled to High-Performance Liquid Chromatography

Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC) equipped with UV detector was used for the extraction and determination of efavirenz in plasma sample. Acetonitrile and chloroform were used as disperser and extraction solvents, respectively. Several parameters, including extraction solvent, the type of dispersion solvent, volume of extraction and dispersion solvents, pH, ionic strength of the media, as well as centrifuging time were optimized. Samples were injected on a reversed-phase C18 analytical column. The mobile phase consisted of 20 mM phosphate buffer (pH=3.0) and acetonitrile (40:60, v/v). The calibration curve of the proposed method was linear in the range of 0.1–100 μg/L. The relative standard deviations (RSD, %) were 3.4–7.5% (n=6) and the limit of detection (LOD) was 0.01 μg/L. The proposed method was applied to the analysis of plasma sample and spiked recoveries in the range of 98.5–102.5% were obtained. The obtained results show that DLLME is a very simple, rapid, sensitive, and efficient analytical method for the determination of efavirenz in plasma.